Advantages of Metal-Free Window Films

3M Company first patented the solar control window film in 1966 to promote energy efficiency by reducing a window’s solar heat gain coefficient (SHGC). Early generation films were dark and reflective in nature, thereby changing the appearance of the glass on which they were installed – something considered taboo for many commercial and residential buildings. Since then, there have been substantial advancements in film technology, ultimately improving a film’s performance, longevity, and appearance.

Advancements in Sun Control Window Film Construction

Understanding basic film construction is necessary to appreciate the advancements in composition materials that have occurred since 1966. The building block of any solar control window film is the polyester layer to which everything else is laminated. On one side of the polyester is an adhesive layer which allows the entire film assembly to stick to the glass on which it is installed. On the other side of the polyester is an insulated layer. It is this insulated layer that gives a film its color and reduces a window’s SHGC. On the other side of the insulated layer is a protective hard coat which allows the film to stand the test of time.

The insulated coating merits great attention given its importance in performance and aesthetics. Advancements in insulated coatings can provide buildings with significant benefits. The most noteworthy advancement is that metal is no longer a necessary component to a film’s insulated coating. Meaning, a film can now lower a window’s SHGC without the use of metal. 

Benefits of Metal-Free Films

A metal-free or non-metalized film provides numerous benefits over a metalized film:

1) Low Reflectivity Without Sacrificing Performance

The historic use of metal for a film’s insulated coating is because metal reflects heat. Silver, bronze, nickel, and even gold, just to name a few, are commonly found in metalized films. Metals tend to be shiny, reflective, and opaque. Incorporating those characteristics in construction means that a film may also be shiny, reflective, and opaque – qualities that will change the appearance of a window and ultimately the building.

Now, aesthetic change may not necessarily be a bad thing. There are times when an aesthetic change is required. For example, a building wants to hide inconsistent window blind drawing heights from the outside world. Or a building may want to rebrand itself to increase its curb appeal and attract new tenants. But, more often than not, stakeholders do not want their building’s appearance to change.

With advancements in insulated coatings, window films are able to reflect and absorb incident energy without the use of metal. These films reduce solar heat gain without being shiny, reflective, and opaque. The change in a window’s appearance is minimal and often not even noticed by the curious observer. Solar heat gain is reduced while the building’s aesthetics remain essentially unchanged. 

2) No Signal Interference (Wi-Fi, 5G, RFID)

Metals are known to block electromagnetic signals such as radio, Wi-Fi, cellular, and RFID. Given their prominent usage by occupants in homes or offices, any loss of signal can have repercussions on productivity, efficiency, and overall enjoyment of space.

Metalized films, especially when installed on all windows, can reduce the strength of incoming electromagnetic signals. To the average building occupant, that could represent a degradation or loss of cell phone service, especially 5G. 5G, while faster than 4G, operates at higher frequencies and are more sensitive to interference caused by nearby metals commonly found in metalized window films.

3) Longer Lifespan

Of the layers that comprise a solar control window film, the insulated coating is most likely to fail first. It is not uncommon for a metalized film to break down in appearance 20 years after installation. A film with a failing metalized layer will have the appearance of alligator skin, thereby impeding views and ruining aesthetics, inside and outside.

Metal-Free Films from 3M

From Post-it® Notes to Scotch™ Tape, 3M is a company known for innovative technology that positively impacts people’s lives. It is not uncommon for 3M to introduce a new product and make continual improvements to it based on customer feedback and advancements in science. And the solar control window film that 3M originally patented in 1966 is no exception.

Realizing the aforementioned disadvantages of metalized window films, 3M introduced two lines of metal-free films that are meant to approximate the performance of metalized films without the associated drawbacks.

1) 3M Prestige Series Window Films

3M introduced its Prestige Series Window Films in 2006. Made of nano-layered polyester, Prestige films reject up to 97% of the sun’s infrared heat when measured from 900 to 1,000nm. Unlike traditional metalized films, Prestige Series are virtually clear and colorless making them practically invisible when installed. In fact, certain Prestige films are less reflective than clear glass! And depending upon the shade, this series allows in as much as 90% of the sun’s natural light.

Available in multiple visible light transmissions (20%, 40%, 50%, 60%, 70% & 90%), they are the perfect solution for buildings and homes that have highly efficient, semi-clear, floor-to-ceiling glass yet are difficult to keep cool during the spring, summer, and fall seasons.

2) 3M Ceramic Series Architectural Films

Unlike competitive ceramic films, 3M Ceramic Architectural Series Films are metal-free. They are for end-users that want a metal-free film but at a more affordable price than 3M Prestige Series.

The non-metalized construction means lower interior and exterior reflectivity as compared to metalized ceramic films offering similar heat rejection. This film series is offered in four various shades (35%, 45%, 60% & 80%) of blue-gray to help end-users find the right balance between performance and aesthetics.

Conclusion

Metalized and non-metalized window films have their place. But as architectural trends change and our reliance on electromagnetic signals increases, the benefits of metal-free films become even more clear – just like the metal-free film itself!

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